CHYME. 35 



Our knowledge of the uses of the gastric juice in the process 

 of digestion, is much clearer than that of the other fluids already 

 described, as the saliva, pancreatic juice, and bile. We know 

 that alimentary matters insoluble in mere water are readily dis- 

 solved by the pepsin of the gastric juice combined with a little 

 free dilute acid, and that some of these substances become 

 chemically changed during the process of solution. 



The intestinal fluid. 



The small intestines, when empty and not irritated, secrete 

 an almost neutral, very viscid fluid, but during digestion, or 

 when irritated, the secretion becomes decidedly acid. We 

 cannot examine this fluid in a state of purity, but it is most 

 probable that in its constitution it is similar to the gastric juice, 

 and that it possesses the property of acting on those substances 

 which have escaped the solvent power of that fluid. According 

 to Tiedemann and Gmelin it contains a large quantity of albu- 

 men; this is, however, most likely due to the pancreatic fluid 

 which becomes mixed with it. It must also be more or less 

 mixed with the biliary secretion. 



On the process of Digestion, and the Chyme. 



By the process of digestion we understand the solution and 

 the modifications that the food undergoes in the stomach and 

 adjoining portion of the intestinal canal, together with the ab- 

 sorption and metamorphosis of the nutrient fluid (chyme) con- 

 tained in the reduced pulpy mass of the food, till it becomes 

 perfect chyle. 



The subject of digestion has attracted much attention for the 

 last seventy years, but unfortunately the results that have been 

 obtained are by no means proportionate to the time and labour 

 involved in the experiments instituted in relation to this de- 

 partment of physiology. 



The discovery and isolation of pepsin forms a new epoch in 

 the chemical history of digestion. It is now in our power to 

 institute experiments on artificial digestion with every prospect 

 of success ; we can examine the new products that are developed, 

 and we shall be thus led to the true understanding of the for- 



